I. The Field of the Invention
The present invention generally relates to the field of medical devices. More specifically, the present invention relates to methods, systems, and devices for manufacturing a self-expanding medical device.
II. Related Technology
The use of intravascular devices to treat cardiovascular diseases is well known in the field of medicine. The need for a greater variety of devices to address different types of circumstances has grown tremendously as the techniques for using intravascular devices has progressed. One type of intravascular device is a stent. Stents are generally cylindrically shaped intravascular devices, which are placed within an artery (or other vessel within the body) to hold it open. The device can be used to reduce the likelihood of restenosis or recurrence of the blocking of a blood vessel. In some circumstances, a stent can be used as the primary treatment device where it is expanded to dilate a stenosis and left in place.
A variety of stent designs have been developed. Examples include coiled wires in a variety of patterns that are expanded after being placed within a vessel on a balloon catheter, helically wound coiled springs manufactured from expandable heat sensitive metals, stents shaped in zig-zag patterns, and self-expanding stents inserted in a compressed state for deployment in a body lumen. One of the difficulties encountered using stents involve maintaining the radial rigidity needed to hold open a body lumen while at the same time maintaining the longitudinal flexibility of the stent to facilitate its delivery and accommodate the often tortuous path of the patient's vasculature. Generally, the greater the longitudinal flexibility of the stent, the easier and more safely it can be delivered to the implantation site.
A stent can have various features. For instance, a stent can have a tubular shape formed from a plurality of interconnected struts and/or legs that can form a series of interconnected rings. In the expanded condition, the stent can have a cylindrical shape to expand in an artery. One preferred material for manufacturing self-expanding stents is NITINOL, an alloy of Nickel and Titanium.
NITINOL, an alloy of Nickel and Titanium, self-expanding stents can be manufactured in a variety of different manners. One typical approach is to laser cut the design of the stent from a tube which dimensions are close to the desired compressed size. The tube is then deburred to clean any imperfections due to the cutting. Cycles of stent expansion and heat treatment are then repeated until the stent reaches its intended dimension for deployment in a vessel.
Unfortunately, current manufacturing processes are cumbersome and in some instance induce cracks in the stent from undesired torque and compression. It is therefore, desirable, to provide a new method of manufacturing self-expanding stents.